This study presents a comprehensive risk assessment of battery vent gas (BVG) from lithium-ion cells, focusing on its dynamic composition and laminar burning velocity (Su). It highlights lithium titanate (LTO) cells, which use Li4Ti5O12 anode, and compares them with NMC, NCA, and LFP chemistries.LTO cells improved safety by mitigating lithium plating and dendrite growth, key causes of internal short circuits and thermal runaway (TR). BVG composition evolves significantly during TR and depends on cell chemistry and state of charge (SoC), affecting combustion behaviour.BVG composition and Su were quantified during different stages of thermal abuse for cells with various chemistries and SoC (50% and 100%). A lab-scale setup with FT-IR and Micro-GC identified gases such as H2, CO, CO2, CH4, HF, and organic carbonates. Additional analyses (FT-IR) identified unburned species, while CHEMKIN-Premix calculated Su and sensitivity factors. Results show that LTO and LFP cells are safer under thermal abuse. At 100% SoC, NMC produced the most hazardous BVG, with higher hydrogen and the highest Su. At 50% SoC, TR was suppressed for LTO and LFP cells.These findings provide key insights into combustion dynamics and support improved mitigation of fire and explosion hazards in lithium-ion batteries.

The rapid expansion of lithium-ion battery (LIB) technology across energy storage and transportation sectors raises significant safety concerns due to potential fire and explosion risks. Thermal runaway (TR) events in LIBs can release flammable gases, thereby posing heightened fire hazards. However, data on the flammability characteristics of gases emitted during thermal failure remain limited. This study addresses this gap by evaluating the laminar burning velocity (Su), a key safety parameter, using both experimental and modeling approaches to understand the influence of cell chemistry on LIB behavior. Three commercial cylindrical cells-Lithium Nickel Cobalt Aluminium Oxide (NCA), Lithium Iron Phosphate (LFP), and Lithium Nickel Manganese Cobalt Oxide (NMC)-were tested at a 100 % state of charge (SoC). Cells were subjected to controlled heating at a rate of 5 degrees C/ min in a laboratory setup equipped with Fourier Transform-Infrared Spectroscopy (FT-IR) and a micro-GC for real-time gas analysis. Major battery vent gas (BVG) components detected during TR event included H2, CH4, CO, CO2, HF, and vapours of electrolyte solvents like dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylene carbonate (EC). The Suvalues were calculated using a one-dimensional laminar premixed flame model within the CHEMKIN software, with continuous gas monitoring throughout the entire thermal failure event. These calculations considered different BVG compositions during specific phases-venting, TR, and overall event phases-each critical depending on cell chemistry. For NCA cells, the TR phase exhibited the most critical BVG composition, while for LFP and NMC cells, the venting phase proved more critical, largely due to H2 emissions. Furthermore, the effect of TR-induced temperature on Suwas evaluated through simulations conducted at 25 degrees C, 150 degrees C, 300 degrees C, and 500 degrees C at 1 atm.

Lithium-ion batteries (LIBs) are a promising energy source for various applications and especially for electric mobility due to their high efficiency, high energy density, and long cycle life. However, the rapid rise of electric vehicles on the road has not been followed by an equally rapid development in the scientific knowledge of LIB fire hazards and technological solutions to predict it and mitigate them. Experimental tests of real-scale electric vehicles are quite limited and hardly consider the burnout of the cars. CFD simulations are a promising tool to model large fires in car parks and ferries based on parameters measured in small-scale tests. However, although CFD models of cars can be found in the literature, the inclusion of the battery pack contribution to the car fire is not trivial. This study outlines a methodology to model the fire spread from one LIB cell to another, which could later be extended to a whole battery pack to obtain a heat release rate (HRR) curve that can be added to that one of the car interiors to predict the HRR of an EV. In particular, the choice of the HRR of the single battery cell and its ignition temperature and the necessary mesh refinement required to predict the ignition of adjacent cell surfaces are highlighted.

Fire suppression and rapid cooling methods are required to reduce the risk of battery fires. However, the liquid and solid residues generated during fire extinguishing pose a risk to the environment and human health. With the aim of correlating the extinguishing efficiency and environmental impact of the residues, fire tests were carried out on NMC lithium-ion pouch cells using different agents, namely water mist, F-500 water additive 2 % (v/v) and CO2. The combination of cell temperature measurements and videos allowed the efficiency of the extinguishing agents to be assessed. It was found that the efficiency of the water-based agents was higher than that of the gaseous agents (cooling rate of 30.5 ± 4.9 °C/s for water mist, 36.5 ± 6.4 °C/s for F-500 and 20.0 ± 1.4 °C/s for CO2). Analysis of solid and liquid residues using gas chromatography and induced coupled plasma showed that the use of F-500 resulted in a higher (one order of magnitude) concentration of VOCs in solid residues compared to the other extinguishing agents. The comparison of these concentrations of VOCs with the limits established for waste (EU Regulation N. 1357/2014) showed that the solid residues did not exceed the concentration limit for classification as hazardous waste. Regarding the concentration of metals, the highest values in the solid and liquid residues are due to Li, Ni and Cu. Based on these values, all solid samples can be classified as carcinogenic and toxic for reproduction. While the concentration of metals in the liquid residues was higher than the limit value that poses a risk to aquatic organisms. The overall results showed the need for site remediation and waste management procedures in the event of a major accident.

Lithium-ion batteries (LIBs) are employed in a range of devices due to their high energy and power density. However, the increased power density of LIBs raises concerns regarding their safety when subjected to external abuse. The thermal behavior is influenced by a number of factors, i.e., the state of charge (SoC), the cell chemistry and the abuse conditions. In this study, three distinct cylindrical Li-ion cells, i.e., lithium nickel cobalt aluminum oxide (NCA), lithium titanate oxide (LTO), and lithium iron phosphate (LFP), were subjected to thermal abuse (heating rate of 5 °C/min) in an air flow reactor, with 100% SoC. Venting and thermal runaway (TR) were recorded in terms of temperature and pressure, while the emitted products (gas, solid, and liquid) were subjected to analysis by FT-IR and ICP-OES. The concentrations of the toxic gases (HF, CO) are significantly in excess of the Immediate Danger to Life or Health Limit (IDLH). Furthermore, it is observed that the solid particles are the result of electrode degradation (metallic nature), whereas the liquid aerosol is derived from the electrolyte solvent. It is therefore evident that in the event of a LIB fire, in order to enhance the safety of the emergency responders, it is necessary to use appropriate personal protective equipment (PPE) in order to minimize exposure to toxic substances, i.e., particles and aerosol.

The demands for Li-ion batteries (LIBs) have recently increased exponentially. They are used in a multitude of applications including electric vehicles (EVs), Energy Storage Systems (ESS) and consumer electronics. However, their chemical composition, high energy content and behaviour under abuse conditions pose a significant risk to safety, human health and the environment. This risk is particularly pronounced with the amount of active materials, especially the organic electrolyte and consequently, with the number of cells constituting the battery. To mitigate the risk, critical points throughout the entire life cycle of a lithium battery must be identified. For this purpose, the analysis of accidents occurring around the world acquires a fundamental importance. The evaluation of the main risks associated with the transport, use and storage of LIBs would allow the improvement of specific prevention measures to reduce the risk of fire and explosion during their use and their storage. Additionally, the improvement of safety procedures to manage accidents involving lithium ion batteries should be considered. Furthermore, it enables the updating of legal and technical standards and the development of more reliable storage systems. The aim of this study is to enhance current knowledge on the factors that may trigger fire involving LIBs through the analysis of accidents and recall databases analysis. An Italian database has been developed which includes data on accidents that occurred during the normal use of batteries, as well as those that occurred in storage facilities, during transport and in the disposal of batteries. One example of the reconstruction of data necessary to enhance a database is presented in this work.

The electric vehicles are a good option for aiming the Energy transition, in a such important sector such as the mobility. The use of a huge quantity of high energy and high power Lithium-Ion Batteries (LIBs) opens the discussion of many topics such as competitiveness compared to other technologies, recycling of the materials and the safety. This paper shows an experimental study based on fire extinguishing tests on NMC Lithium-Ion pouch cells, each with approximately 100 Wh energy stored. Different extinguishing agents were tested: Foam, Aqueous Vermiculite Dispersion (AVD). After tests, solid samples were taken from the burnt cell and the residue extinguishing liquid was collected. Gases produced from the combustion of the cell were also sampled during the test and collected in gas bags. Chemical analyses were performed on solid, liquid and gaseous residues in order to evaluate presence of hazardous compounds for health and environment. Gas Chromatography Mass Spectrometry and a Fourier-transform Infrared Spectroscopy were used to handle this type of analysis. The aim of this experimental work is to identify the hazardous compounds present in the residue of LIB after the fire is extinguished (i.e. electric vehicles) to evaluate their health and environmental impact and then to propose a methodology for their treatment or disposal. In particular, a comparison between different extinguishing agents is reported.

The advantages of Lithium-ion batteries (LIBs) are well known, anyway the LIBs are even considered hazardous products. In fact, outside the safety windows the Li-ion cells can undergo to an abuse that leads to the degradation of the internal components with the release of gases, vapour, and solid products. The reactivity of the LIBs and the relative products composition is strictly correlated to the chemical composition of the internal components. Because of a lack of regulation, safety data sheets (SDSs) of Li-ion cells are not mandatory but, generally they are available. However, there is a gap between the information reported in the SDS and the internal chemical composition, and usually the quantity of components is expressed as a range of weight percentages, and the chemical composition is not well specified. The most common lack of information concerns the electrolyte, which is usually defined as a mixture of organic carbonates without reporting the type of solvents (e.g., dimethyl carbonate, diethyl carbonate, and ethylene carbonate), the ratio between these components, and possible additives. The aim of this work was to characterize the internal components of various cylindrical 18650 cells available on the market, i.e., cell with Lithium Nickel Cobalt Aluminium Oxide (NCA) as cathode and graphite (C) or Lithium Titanate Oxide (LTO) as anode, and cells with Lithium Iron Phosphate (LFP) as cathode and C as anode. For this purpose, the cells were disassembled in a glovebox filled with argon (O2 and H2O = 0.1 ppm) and then the different components were analysed by various techniques to define their chemical composition, i.e., metals of the electrodes by ICP-OES, the electrolyte by GC-FID and SPME-GC-MS, and the separator by ATR-FT-IR and DSC. The identification of those compounds is fundamental to understand the reactions occurring inside the cells and to evaluate the risks for human health and environment.

The thermal runaway (TR) is the main safety concern of lithium-ion batteries (LIBs). Methods for predicting and preventing TR are critical to achieve greater battery safety. Many researchers have studied the reactions that take place inside the cell and that because of their exothermicity trigger the TR. In this work the coupled electrochemical-thermal model for a lithium-ion cell was extended with contributions from exothermic reactions based on an Arrhenius law to model mechanisms of abuse, which could lead to a thermal runaway. Firstly, differential scanning calorimetry (DSC) tests were conducted on the individual components of the cell to characterize the reactions of the TR process in terms of onset temperature, thermal and kinetic parameters. The kinetic parameters of each reaction were identified by the Kissinger method. Then the thermal and kinetics parameters of the reactions occurring during the thermal runaway together with the phenomena involving the electrolyte (i.e., evaporation, boiling and venting) were included in the Battery and Fuel Cell Module of COMSOL Multiphysics simulator, to simulate the behaviour of a cylindrical 18650 cell under thermal abuse conditions. In particular, the results of the model appear to agree with the experimental data, concerning to a NCA 18650 cell subjected to radiative heat flux in a cone calorimeter.

Lithium-ion Batteries (LIBs) are characterized by high energy and power density and long life and are currently used in many applications from portable devices to energy storage systems. These features increase safety concerns, especially when these devices are subject to thermal, mechanical, or electrical abuse. Abuse can lead to exothermic reactions of cell components and with each other, causing a rapid increase in temperature, called Thermal Runaway (TR), and pressure. The response to abuse depends on the physical-chemical characteristics of Li-ion cells, such as chemical composition and State of Charge (SOC). To study the effect of chemical composition, three different 18650 Li-ion cells were tested, i.e., Lithium Titanate Oxide (LTO), Lithium Iron Phosphate (LFP) and Lithium Nickel Cobalt Aluminium Oxide (NCA), at the same SOC (100 %). The cells were subjected to thermal abuse tests in a tubular reactor connected at the output to an online Fourier-transform infrared spectroscopy (FT-IR). All events, i.e., Current Interrupt Device (CID) activation, venting and TR, were recorded, and the gases emitted were traced back to the reactions that take place inside the cell. By comparing the response of the cells with different composition it was found that onset of TR occurs at lower temperature for NCA than the other cells (207 vs 233-234 °C), but the maximum temperature reached during TR by the NCA is higher (579 vs 310-338 °C). Regarding toxic emissions, for all three cells the values of hydrofluoric acid (HF) and carbon monoxide (CO) significantly exceed the Immediately Dangerous to Life or Health Limit (IDHL) defined by the National Institute for Occupational Safety and Health set at 30 ppm for HF and 1200 ppm for CO in 30 min, with maximum concentration of HF between 824 - 893 ppm and the maximum concentration of CO changing according to the chemistries: 231990 ppm for NCA, 140728 ppm for LTO and 97140 ppm for LFP.

Thermal abuse of lithium-ion batteries (LIBs) leads to the emission of gases, solids, fires and/or explosions. Therefore, it is essential to define the temperatures at which key events occur (i.e., CID activation, venting, and thermal runaway (TR)) and to identify the related emissions for identifying the hazards to which people and especially rescue teams are exposed. For this purpose, thermal abuse tests were performed on commercial lithium nickel cobalt aluminum oxide (NCA) 18650 cells at 50% state of charge in a reactor connected to an FT-IR spectrometer by varying test conditions (feed gas of N2 or air; heating rates of 5 or 10 °C/min until 300 °C). In particular, the concentrations of the gases and the composition of the condensed-phase emissions were estimated. As regards gases, a high concentration (1695 ppmv) of hydrofluoric acid (HF) was measured, while the emissions of condensed matter consisted of organic compounds such as polyethylene oxide and paraffin oil, and inorganic compounds containing Li (0.173 mg/m3) and Al (0.344 mg/m3). The main safety concerns were caused by the temperatures (564 ± 85 °C) reached by the cell during TR, by the HF concentration which exceeded the toxicity limits of 30 ppm, the IDLH defined by the NIOSH, and the diameter of the particles (1.54 ± 0.69 µm) that rose the PM2.5 concentration. These results are also useful for identifying personal protection equipment for rescue teams.

Lithium-ion batteries (LIBs) are employed when high energy and power density are required. However, under electrical, mechanical, or thermal abuse conditions a thermal runaway can occur resulting in an uncontrollable increase in pressure and temperature that can lead to fire and/or explosion, and projection of fragments. In this work, the behavior of LIBs under thermal abuse conditions is analyzed. To this purpose, tests on NCA 18,650 cells are performed in a cone calorimeter by changing the radiative heat flux of the conical heater and the State of Charge (SoC) of the cells from full charge to deep discharge. The dependence of SoC and radiative heat flux on the thermal runaway onset is clearly revealed. In particular, a deep discharge determines an earlier thermal runaway of the cell with respect to those at 50% and 100% of SoC when exposed to high radiative heat flux (50 kW/m2). This is due to a mechanism such as an electrical abuse. Cell components before and after tests are investigated using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy—Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray Diffraction (XRD) to determine the structural, morphological, and compositional changes. It results that the first reaction (423–443 K) that occurs at the anode involves the decomposition of the electrolyte. This reaction justifies the observed earlier venting and thermal runaway of fully charged cells with respect to half-charged ones due to a greater availability of lithium which allows a faster kinetics of the reaction. In the cathode residues, metallic nickel and NO are found, given by decomposition of metal oxide by the rock-salt phase cathode.

Lithium-Ion Batteries (LIBs) convert the chemical energy obtained from the intercalation of lithium ions in the cathode material of the cell into electrical energy. They are called secondary batteries because are rechargeable. They are currently applied in portable applications (e.g., smartphone, tablet, personal computer), in mobility (e.g., Electrical Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs)) and Energy Storage Systems (ESS) for the higher energy and power densities than traditional batteries. LIBs due to their energy content and chemical composition are considered dangerous products that must be handled and used according to the manufacturer's safety indication, defined by the safety window (voltage and temperature ranges). If LIBs are used in conditions outside that window, they are subject to external and/or internal abuse, classifiable as mechanical, electrical, and thermal abuse. These conditions lead to a change in the chemical composition, due to melting of the separator and subsequent chemical reactions, and in the internal pressure, with consequent opening of the safety valve, when present, or of an area of the cell with less resistance welding. Because of the exothermicity of the reactions, the temperature of the system drastically increases in a short time giving rise to release of gas, vapours, fire and/or explosion with the projection of fragments.